Deceased Humpback Whale - Joshua Meza-Fidalgo, 2020

Deceased Humpback Whale - Joshua Meza-Fidalgo, 2020

Rationale and Research Questions

Marine mammal and sea turtle strandings can be unusual events or indicators of problems in our ocean ecosystems. Seeing patterns in the strandings of marine mammals and sea turtles can be indicative of more complex issues that may not be transparent. Some example of these issues could be viral outbreaks in lower trophic level populations or toxic algal blooms that kill off all sea life in the area. Because humans demand and consume seafood, understanding the problems that arise are essential to preventing the consumption of contaminated seafood along with the management of fisheries. By studying marine mammal and sea turtle strandings, we get insight on the health of our oceans.

Our objective is to analyze animal strandings over the years to see if there any trends in the quantity of strandings for each family (cetaceans, odontocetes, mysticetes, and pinnipeds). We have decided to look at the total number of strandings per year for all families, the changes in strandings over the years for each family and the seasonality differences across all years for each family.

Dataset Information

Table 1: Dataset Information
Detail Description
Data Source OBIS-SEAMAP - Mystic Aquarium
Retrieved From https://seamap.env.duke.edu/dataset/945
Variables Used Family, Common Name, Species Name, Date, Year, Month, Latitude, Longitude, Total Strandings, Strandings by Species
Data Range March 18, 1976 to December, 29, 2011

The dataset that we chose to work with is the Mystic Aquarium’s marine mammal and sea turtle stranding data that started in 1976 until 2011. However, there was only one stranding record in 1976, so that point was excluded from our analysis. The rest of the data started in 1990 and was concluded in 2011. It contains the number of whale (odontocetes and mysticetes), pinniped, and sea turtle strandings that occurred along the coasts of Connecticut, Rhode Island and Fishers Island, New York, USA. There were a total of 1140 strandings; within these strandings, 155 were odontocetes, 50 were mysticetes, 679 were pinnipeds, and 256 were sea turtles.

The dataset has a latitude that ranges from 41.00 to 41.86 while the longitude ranges from -73.65 to -71.10. We data was provided using the datum WGS 1984 (4326) and we performed a data transformation into UTM 19 (32619) for geospatial analysis. The data was wrangled to contain only the variables that we were interested in using. We then selected parts of the data based off of the Common Name of the species to create datasets that were easier for us to use in our analysis. This helped us divide the data into four groups: odontocetes, mysticetes, pinnipeds, and sea turtles. We initially looked at total yearly strandings for trends in the data for each family. After we analyzed the data on a monthly basis to help give insight to seasonal stranding trends for each family.

##  [1] "dataset_id"      "row_id"          "latitude"        "longitude"      
##  [5] "species_name"    "scientific_name" "common_name"     "itis_tsn"       
##  [9] "group_size"      "series_id"       "date_time"       "timezone"       
## [13] "ds_type"         "platform"        "provider"        "lprecision"     
## [17] "tprecision"      "oceano"          "notes"           "last_mod"
## [1] "Family"       "common_name"  "species_name" "Date"         "Year"        
## [6] "Month"        "latitude"     "longitude"

Exploratory Analysis

We initially decided that it would be best to look at the data wholisticlly to get a better feel for the trends in teh data. We first analyzed the total number of strandings per each family, as seen in Figure 1. To better see the data, we divided summed the strandings of each family for each year from 1990 to 2011, as seen in Figure 2. To see if there could be seasonal trends for the entire data set, the data was grouped by month for each family from the years 1990 to 2011, as seen in Figure 3. Finally, to have a geospatial understanding of our data, Map 1 was created.

Figure 1: Total Strandings per Family

Figure 2: Total Strandings per Year

Figure 3: Total Strandings per Month

Map 1: Geospatial Exploration of each Family

Analysis

  1. Pinnipeds:

Question 1: Are there years or months where the number of pinniped strandings are significantly different?

Question 2: Are there trends in pinniped strandings based off of this dataset?

  1. Whales:

Question 1: Are there years or months where the number of toothed whales (odontocetes) strandings are significantly different?

Question 2: Are there trends in toothed whale (odontocetes) strandings based off of this dataset?

Question 3: Are there years or months where the number of baleen whales (mysticetes) strandings are significantly different?

Question 4: Are there trends in baleen whale (mysticetes) strandings based off of this dataset?

  1. Turtles:

Question 1: Are there years or months where the number of turtle strandings are significantly different?

Question 2: Are there trends in turtle strandings based off of this dataset?

Summary and Conclusions

Deceased Fin Whale - Joshua Meza-Fidalgo, 2020

Deceased Fin Whale - Joshua Meza-Fidalgo, 2020

References

Data: https://seamap.env.duke.edu/dataset/945

  1. Halpin, P.N., A.J. Read, E. Fujioka, B.D. Best, B. Donnelly, L.J. Hazen, C. Kot, K. Urian, E. LaBrecque, A. Dimatteo, J. Cleary, C. Good, L.B. Crowder, and K.D. Hyrenbach. 2009. OBIS-SEAMAP: The world data center for marine mammal, sea bird, and sea turtle distributions. Oceanography. 22(2):104-115.

  2. Smith, A. 2014. Mystic Aquarium’s marine mammal and sea turtle stranding data 1976-2011. Data downloaded from OBIS-SEAMAP (http://seamap.env.duke.edu/dataset/945) on 2022-04-02.

Photos: Special thanks to Joshua Meza-Fidalgo for providing whale photos for us to use.